wk 12- haematology

• Blood Sciences


  • Comprehensive integrated pathology service
  • 24/7 service - core hours 9-5 but include early, late, day and night shifts
  • Diagnostic aid to clinicians within the hospital, externally to GP's and other users
  • Electronic links for requesting and results
  • Collection service for samples
  • Consultant advisory service
  • Provides the laboratory handbook/department website plus guidelines
  • Quality monitored by internal and external Quality Assurance and UKAS accreditation
• Technical Validation


  • Using Quality Control samples to ascertain if an instrument is performing – producing the results we expect it to
  • Using a system to assess the quality of those results
  • Using acceptance criteria to assess and accept results before release
• Clinical Validation


  Diagnoses documented in a patient's record must be substantiated by clinical criteria generally accepted by the medical community
• Blood Sciences


  The laboratory's role
• Reference range vs Quality Control ranges

  • Gaussian (normal) distribution is used in two ways: The QC range is the 3SD range of acceptable results of QC samples, The reference range is the results expected in a population with no disease present (ie normal)
  • Both use 95% confidence limits
• The laboratory's role


  • Comprehensive integrated pathology service
  • 24/7 service - core hours 9-5 but include early, late, day and night shifts
  • Diagnostic aid to clinicians within the hospital, externally to GP's and other users
  • Electronic links for requesting and results
  • Collection service for samples
  • Consultant advisory service
  • Provides the laboratory handbook/department website plus guidelines
  • Quality monitored by internal and external Quality Assurance and UKAS accreditation
• Reference range


  • In Blood sciences, results are often reported as concentrations
  • Concentrations change if the amount of the analyte changes or if the volume of solvent changes
  • Variability of results is caused by both analytical factors and biological factors
  • The reference range supplied with the test result is only a guide to the probability of the results being statistically 'normal' or 'abnormal'
  • Different reference intervals may apply depending on the age or sex of the patient
  • If a result does not accord with that expected for the patient, the finding should be discussed with the laboratory reporting office and a repeat test arranged
• Pathology Results


  The Expectation
• Specificity and Sensitivity


  • Figure 3.3 shows the effect of changing the 'diagnostic cut-off value' on test specificity and sensitivity
  • Normal is no disease present
  • Analytical variation is generally less than that from biological variation
  • Biochemical test results are usually compared to a reference interval chosen arbitrarily to include 95% of the values found in healthy volunteers
  • This means that, by definition, 5% of any population will have a result outside the reference interval
  • In some situations it is useful to define 'action limits', at which appropriate intervention
  • There is often a degree of overlap between the disease state and the 'normal value'
  • An abnormal result in a patient who is subsequently found not to have the disease is called a 'false positive'
  • A 'normal result' in a patient who has the disease is a 'false negative'
• Authorisation/Validation of Results


  1. Technical Validation

  2. Using Quality Control samples to ascertain if an instrument is performing – producing the results we expect it to

  3. Using a system to assess the quality of those results

  4. Using acceptance criteria to assess and accept results before release
• Haematology


  The study of blood and blood forming organs
• Clinical Validation


  Diagnoses documented in a patient's record must be substantiated by clinical criteria generally accepted by the medical community
• Haematology in Healthcare


  • Biomedical Scientists in Haematology
  • Overlaps with other disciplines
• Reference range vs Quality Control ranges

  • Gaussian (normal) distribution is used in two ways: The QC range and The reference range
  • The QC range is the 3SD range of acceptable results of QC samples
  • The reference range is the results expected in a population with no disease present (ie normal)
  • Both use 95% confidence limits
• The Main Tests Performed by Routine Haematology


  • Haemoglobin - Hb g/l
  • Red Blood Count - RBC x 10^12 /L
  • Mean Cell Volume - MCV fl
  • Haematocrit - HCT %
  • White Blood Cells WBC x 10^9 /L
  • Differential White Cell Count (Diff x 10^9 /L)
  • Neutrophils
  • Lymphocytes
  • Monocytes
  • Eosinophils
  • Basophils
  • Platelet Count - PLT x10^12 /L
• The Reference range


  • Results are often reported as concentrations
  • Concentrations change if the amount of the analyte changes or if the volume of solvent changes
  • Variability of results is caused by both analytical factors and biological factors
  • The reference range supplied with the test result is only a guide to the probability of the results being statistically 'normal' or 'abnormal'
  • Different reference intervals may apply depending on the age or sex of the patient
  • If a result does not accord with that expected for the patient, the finding should be discussed with the laboratory reporting office and a repeat test arranged
• Red Blood Count - RBC x 10^12 /L

  • This is a count of the number of red blood cells (erythrocytes) in the blood
  • Red blood cells are the only cell in the body without a nucleus
  • They are just a bag in which haemoglobin is carried around the body via the arteries, veins and capillaries
  • Red cells are a biconcave disc shape (doughnut)
  • This shape allows the cell to bend and squeeze through very narrow spaces within the circulation
  • 1 litre of blood contains 10 million million red blood cells
  • Each red cell circulates for 120 days and is then recycled by the liver and spleen
  • Normal ranges: Male 4.5-6.5 x 10^12 /L, Female 3.8-5.8 10^12 /L
• Specificity and Sensitivity


  • False negatives and False positives
  • Normal is no disease present
  • Analytical variation is generally less than that from biological variation
  • Biochemical test results are usually compared to a reference interval chosen arbitrarily to include 95% of the values found in healthy volunteers
  • This means that, by definition, 5% of any population will have a result outside the reference interval
  • In some situations it is useful to define 'action limits', at which appropriate intervention
  • There is often a degree of overlap between the disease state and the 'normal value'
  • An abnormal result in a patient who is subsequently found not to have the disease is called a 'false positive'
  • A 'normal result' in a patient who has the disease is a 'false negative'
• Mean Cell Volume - MCV fl

  • The Mean Cell Volume (MCV) is a measurement of the average size of the red cells
  • This is useful when investigating anaemia
  • The normal range is: Male 80-100 fl, Female 80-100 fl
  • The MCV is decreased in anaemia caused by iron deficiency (microcytic)
  • The MCV is increased in anaemia caused by B12 deficiency (macrocytic)
• Haematology


  The study of blood and blood forming organs
• Haematocrit - HCT %

  • This is as measurement of how much space the red cells take up in a blood sample
  • Normal range: Male 0.42-0.52, Female 0.36-0.47
  • The Haematocrit is useful when hidden blood loss is suspected
• Haematology in Healthcare


  • Biomedical Scientists in Haematology
  • Overlaps with other disciplines
• White Blood Cells WBC x 10^9 /L

  • White blood cells are also called leucocytes
  • The white blood count is a count of the number of white cells in the blood
  • White blood cells protect the body against infections
  • Normal range: Male 4-11 x 10^9 /L, Female 4-11 x 10^9 /L
• The Main Tests Performed by Routine Haematology


  • Haemoglobin
  • Red Blood Count
  • Mean Cell Volume
  • Haematocrit
  • White Blood Cells
  • Differential White Cell Count
  • Neutrophils
  • Lymphocytes
  • Monocytes
  • Eosinophils
  • Platelet Count
• Differential White Cell Count (Diff x 10^9 /L)

  • Neutrophils
  • Lymphocytes
  • Monocytes
  • Eosinophils
  • Basophils
• Haemoglobin


  Hb g/l
• Neutrophils


  • Neutrophils are the most abundant white cell
  • Neutrophils fight infection by destroying bacteria by phagocytosis
  • Increased numbers of neutrophils is known as neutrophilia
  • Decreased number of neutrophils is known as neutropenia
  • Neutrophilia is common in infections
  • Normal range:2.5-7.5 x10^9 /l
• Red Blood Count


  • RBC x 10^12 /L
  • Count of the number of red blood cells (erythrocytes) in the blood
  • Red blood cells are the only cell in the body without a nucleus
  • They are just a bag in which haemoglobin is carried around the body via the arteries, veins and capillaries
  • Red cells are a biconcave disc shape (doughnut)
  • This shape allows the cell to bend and squeeze through very narrow spaces within the circulation
  • 1 litre of blood contains 10 million million red blood cells
  • Each red cell circulates for 120 days and is then recycled by the liver and spleen
  • Normal ranges: Male 4.5-6.5 x 10^12 /L, Female 3.8-5.8 10^12 /L
• Lymphocytes


  • Lymphocytes are the second most abundant white cell
  • Lymphocytes fight viral infections and play an important role in immunity
  • Lymphocytosis is found in viral infections
  • When fighting a virus, lymphocytes change shape and colour and are known as atypical or reactive lymphocytes
  • These cells are producing antibodies against the virus
• Mean Cell Volume


  • MCV fl
  • Measurement of the average size of the red cells
  • Useful when investigating anaemia
  • Normal range: Male 80-100 fl, Female 80-100 fl
  • Decreased in anaemia caused by iron deficiency (microcytic)
  • Increased in anaemia caused by B12 deficiency (macrocytic)
• Monocytes


  • Monocytes can be considered general scavenger cells
  • They ingest and destroy bacteria, viruses and any other particals considered foreign by the body
  • Monocytes circulate in the blood before entering the tissues where they undergo transformation to become macrophages
  • Monocytosis is associated with chronic bacterial infections such as TB
• Haematocrit


  • HCT %
  • Packed Cell Volume - PCV
  • Measurement of how much space the red cells take up in a blood sample
  • Normal range: Male 0.42-0.52, Female 0.36-0.47
  • Useful when hidden blood loss is suspected
• Eosinophils


  • They target foreign material too large for neutrophils or monocytes to handle
  • Eosinophilia is associated with allergic disorders such as asthma, eczema and hay fever
  • In less developed countries, where hygiene is poor, eosinophilia is often associated with parasitic infections such as worms
• White Blood Cells


  • WBC x 10^9 /L
  • Also called leucocytes
  • Count of the number of white cells in the blood
  • White blood cells protect the body against infections
  • Normal range: Male 4-11 x 10^9 /L, Female 4-11 x 10^9 /L
• Platelet Count - PLT x10^12 /L


  • Platelets are the smallest cell found in the blood
  • Platelets main functions include: (1) Acting as a mechanical plug when small vessels are damaged, (2) Releasing trigger factors needed for normal blood clotting
• Differential White Cell Count


  • Diff x 10^9 /L
  • White blood cells can be divided into 5 different types: Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils
  • Each type of white cell has a different function
• Why do we do Full Blood Counts?

  • As an aid to diagnosis
  • As an aid to the monitoring of treatment
  • As an aid to the confirmation of cure
• Neutrophils


  • Neutrophils are the most abundant white cell
  • Neutrophils fight infection by destroying bacteria by phagocytosis
  • Increased numbers of neutrophils is known as neutrophilia
  • Decreased number of neutrophils is known as neutropenia
  • Neutrophilia is common in infections
  • Normal range:2.5-7.5 x10^9 /l
• FBC As an Aid to Diagnosis

  • A full blood count is often the first screening test requested when ill health is suspected
  • The FBC can be used to detect signs of: Anaemia, Infection, Haematological malignancy
• Lymphocytes

  • Lymphocytes are the second most abundant white cell
  • Lymphocytes fight viral infections and play an important role in immunity
  • Lymphocytosis is found in viral infections
  • When fighting a virus, lymphocytes change shape and colour and are known as atypical or reactive lymphocytes
  • These cells are producing antibodies against the virus